The present invention relates gnerally to honing tools and more especially to honing tools employing both abrading and guiding elements urged into contact with a workpiece independent of one another.
Honing is a process where through numerous reciprocating and rotating passes, a relatively small amount of material is removed from a surface by means of abrasive elements. The abrading action occurs over a wide surface area rather than on a line of contact as in a grinding operation. The honing tool itself comprises a holding device or body of generally cylindrical configuration containing several generally oblong abrasive elements arranged in a circular pattern in which abrasive elements are forced against a workpiece by a wedging action, for example, of expander plates, forcing those abrasive elements radially outwardly. Such reciprocable and rotatable honing tools carrying such circumferentially spaced abrasive elements or honing stones have been utilzed for many years to hone cylindrical bores in workpieces, such as, for example, the cylindrical bores for internal combustion engines.
It has been proposed, for example, in U.S. Pat. No. 3,861,091, to avoid wearing of the honing tool body by providing fixed guide elements attached to that body, which approach, while it may avoid body wear, does require that the abrasive members and guide members be replaced frequently.
It has also been proposed, for example, in the honing of interrupted bores, such as might be encountered in hydraulic valve bodies, to provide tool guides disposed about the periphery of the tool in much the same manner as the abrasive elements, which tool guides are urged simultaneously with the abrasive elements into contact with the workpiece to maintain tool alignment relative to that workpiece. With such a proposed system, overcutting problems of thin sections of such an interrupted bore are diminished, however, the abrasive elements and guides are forced to wear at substantially the same rate necessitating the replacement of the guides each time the abrasive elements are replaced. Such replacement adds materially to the cost of the honing operation.